1. Field of the Invention
The present invention relates to improvements in automobile sun visors and more particularly, to a composition and article of manufacture providing a particular reduction in transmission of light across the spectrum of electromagnetic energy radiated by the sun and impingent upon the operator of a vehicle.
2. Description of the Prior Art
Automobile sun visors serve to shade the eyes of a vehicle occupant from destructive components of visible light, primarily glare produced by direct or reflected sunlight. Generally, automobile sun visors consist of an opaque, completely non-transmissive sheet material positioned between the occupant of the automobile and the sun light directed toward the occupant's eyes. Nearly all automobile sun visors are pivotable so they can be rotated away from the occupant's line of vision, if the occupant desires.
Many attempts have been made to modify the general form of the automobile visor made of either an inorganic oxide such as glass, or of a plastic, to assist a vehicle occupant in reducing glare, defined herein as harsh, uncomfortably bright light resulting from an intense source of electromagnetic radiation, principally within the visible spectrum.
Externally applied extensions have been produced to increase the effective area of an automobile sun visor. One of the earlier efforts is found in the Sun Visor Extension For Vehicle issued to Barnhart (U.S. Pat. No. 3,853,370), which shows a sun visor extension for vehicles. This extension uses a clamping base designed to attach to an automobile sun visor, with a retractable and extendable sheet forming a visor attached to the clamping base. This sun visor extension allows an occupant to effectively increase the size of an existing automobile sun visor by extending the visor sheet. A transparent or opaque visor sheet fabricated from a colored or tinted plastic material is said to be preferred in order to shade an occupant's eyes when the sun is low on the horizon, although I have discovered that type of visor fails to provide protection that is satisfactory to most motorists.
Another design is found in the Extension Unit For Sun Visor, issued to Karford (U.S. Pat. No. 4,792,176), which shows an extension unit for a sun visor. This extension unit includes two shields and is externally applied to an automobile sun visor. One shield is opaque and may be extended in a horizontal direction to block irritating light from obliquely entering an occupant's eyes. The other shield may be either tinted, polarized or completely opaque, and may be extended and retracted in the vertical direction to block the passage of light from entering an occupant's eyes or to reduce glare, depending upon whether the shield is constructed of tinted, polarized or completely opaque material.
The Sun Glass Attached To Sun Visor of Nakata (Japanese patent 64-63420), briefly mentions an accessory to an automobile sun visor which is electrically or manually controlled and slidably or turnably attached to the visor. The accessory is made from one of either colored glass, a colored plastic board, glass with a film attached to one surface of the glass, or a plastic board with a film s attached to one surface of the plastic board. Other efforts, such as the slidably adjustable extension glare screen found in the Automobile Sun Shield of U.S. Pat. No. 4,978,160 issued to H. Welschoff, or in the Sun Visor For Vehicles of U.S. Pat. No. 2,228,209 issued to C. C. Harrington, rely upon a rectangular translucent panel of any suitable material and teach nothing more than Celluloid, Cellophane and colored silk as suitable translucent materials. I have found that the performance of this type of device is less than acceptable.
Although these and other designs for automobile visors have been attempted over the past several decades, I have discovered that they have many drawbacks and do not adequately address problems attributable to sun glare and problems caused when the sun is either within the driver's field of view or is directly within a driver's line-of-sight. I have become aware of the difficulty in intelligibly distinguishing traffic signals, pedestrians, and other vehicles in the direction of travel when the sun is low on the horizon and within the same line of sight as the other vehicles. Lighted traffic signals in substantially the same line of sight as the sun are particularly difficult to see and even more difficult to watch in order to timely distinguish either their visual message or changes in that visual message, even through a conventional tinted visor. I have found that comparable difficulties are encountered by aircraft pilots. Conventional designs for opaque sun visors typically supplied by a vehicle manufacturer, or opaque extension units, completely block the direct transmission of sunlight to the occupant's eyes, but the consequent narrowing of the driver's field of view and concomitant obstruction of the drivers view of nearby objects often results in a grave risk of collision when the vehicle strikes an object hidden by such opaque sun visors. I have found that light filters permanently incorporated into a windshield are limited by Federal law to a minimum of seventy percent (70%) luminance transmission and are restricted to the lesser of the portion of the windshield above the AS1 line or the top five inches, providing little benefit when the sun is near the horizon. I have also found that conventional tinted visors only slightly moderate the blinding effect created when the sun is near the horizon, failing to eliminate glare caused by direct and reflected transmission of visible sunlight into the eyes of the operator of a vehicle sufficiently to permit the operator to comfortably view nearby objects.